Convert color into pencil shading
The renderer measures luminance, blurs it at a scale tied to image size, and applies a color-dodge relationship to expose edges. Wherever the blurred copy and the original differ, dark strokes survive; wherever they match, the result brightens toward paper. Color retention then mixes the source channels back through that drawing layer.
Pencil detail changes the neighborhood used for the comparison. Small neighborhoods pick up fine texture such as hair and fabric weave, while large ones keep only major outlines.
Paper texture and stroke angle
Paper texture adds directional line variation at the selected stroke angle rather than placing a bitmap texture over the photo. Because the lines are generated relative to image size, a 35° stroke pattern looks the same in the preview and in the full-resolution download.
Angles between 30° and 60° read as natural hand shading. Horizontal or vertical strokes look more mechanical, which can suit architecture or technical subjects.
Example: portrait to illustration
For a head-and-shoulders portrait, set Pencil detail near 40 so skin stays smooth while eyes and hair keep their line work, raise Color retention to about 80 for an illustrated-photo result, and keep Paper texture under 30 so the grain does not compete with facial features.
For a loose sketch of a building or street scene, push detail above 70 and drop Color retention to 30. The extra edges supply the hatching and the reduced color leaves room for the paper to show.
Sources that resist the effect
Heavily compressed screenshots and low-light phone photos produce broken, noisy strokes because JPEG artifacts register as edges. Motion blur removes the luminance differences the dodge step needs, leaving large empty regions. Sharpen or crop such sources before converting, or choose a frame with more defined boundaries. Check small text and logos before export: paper texture can make them unreadable even when the drawing around them looks right.